add darwin test configurations (#525)

dev/darwin-checks.nix

@@ -0,0 +1,17 @@
+{
+  inputs,
+  prefix,
+  self,
+  pkgs,
+}:
+let
+  lib = pkgs.lib;
+
+  darwinConfigurations = import ./darwin-test-configurations.nix { inherit inputs self pkgs; };
+
+  darwinChecks = lib.mapAttrs' (name: value: {
+    name = "${prefix}-${name}";
+    value = value.config.system.build.toplevel;
+  }) (lib.filterAttrs (_name: value: value != null) darwinConfigurations);
+in
+darwinChecks

dev/darwin-test-configurations.nix

@@ -0,0 +1,67 @@
+# We use the darwinConfigurations to test all the modules below.
+#
+# This is not optimal, but it gets the job done
+{
+  inputs,
+  self,
+  pkgs,
+}:
+let
+  lib = pkgs.lib;
+
+  darwinSystem =
+    args: import "${toString inputs.nix-darwin}/eval-config.nix" ({ inherit lib; } // args);
+
+  # some example configuration to make it eval
+  dummy =
+    { config, ... }:
+    {
+      networking.hostName = "example-common";
+      system.stateVersion = 5;
+
+      # Don't reinstantiate nixpkgs for every eval.
+      # Also important to have nixpkgs config which allows for some required insecure packages
+      nixpkgs = {
+        inherit pkgs;
+      };
+    };
+in
+{
+  # General
+  example-common = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.common
+    ];
+  };
+  example-server = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.server
+    ];
+  };
+  example-desktop = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.desktop
+    ];
+  };
+  example-mixins-terminfo = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.mixins-terminfo
+    ];
+  };
+  example-mixins-telegraf = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.mixins-telegraf
+    ];
+  };
+  example-mixins-trusted-nix-caches = darwinSystem {
+    modules = [
+      dummy
+      self.darwinModules.mixins-trusted-nix-caches
+    ];
+  };
+}

flake.nix

@@ -60,6 +60,12 @@
               inherit (self') formatter;
             }
             // packages
+            // (lib.optionalAttrs (pkgs.stdenv.hostPlatform.system == "aarch64-darwin") (
+              import ./dev/darwin-checks.nix {
+                inherit inputs self pkgs;
+                prefix = "darwin";
+              }
+            ))
             // (lib.optionalAttrs isLinux (
               import ./dev/checks.nix {
                 inherit self pkgs;